Process for the resolution of gaseous mixtures



M. FRANKL PROCESS FOR THE RESOLUTION OF GASEOUS MIXTURES June 22', 1937.

2 Sheets-Sheet 1 Filed Jan. 26, 1934 R/ W NA up f w m M wi 2% W W Wm June 2 2, 1937. I FRANKL 2,084,334"

PROCESS FOR THE RESOLUTION OF GASEOUS MIXTURES Filed Jan. 26, 1934 2 Sheets-Sheet 2 k5 INVENTOR Y My mm; F/mw/L RNEYS Patented June 22, 1937 rnooess FOR THE PATENT OFFICE RESOLUTION or 658- 5 EOUS MIXTURES Mathias Frankl, Augsburg, Germany, assignor to American Oxythermic Corporation, New York, N. Y., a corporation of Delaware Application January 26, 1934, Serial No. 708,367

In Austria February 1, 1933 20 Claims.

The invention relates to a process for the resolution of a gaseous mixture into components. More particularly, it relates to a process for the resolution of air into oxygen and nitrogen, and

5 includes correlated improvements and discoveries whereby the separation of gaseous mixtures is enhanced.

In the resolution of a gaseous mixture into its principal constituents, as for example, air into oxygen and nitrogen, or simply for the separation -of a portion of the lower boiling constituent, as nitrogen therefrom, it is necessary to liquefy about one-half of the gaseous mixture, thus for air, from about 45-60%. The quantity of liquid produced depends upon the volume of lower boiling constituent it is desired to separate. The liquid containing a lower boiling constituent may be enriched by means of rectification, and the enriched liquid so produced evaporatedand used or stored as desired.

An advantageous procedure for effecting, such a resolution is described and claimed in my copending application Serial No. 568,715, filed October 14, 1931, now matured into Patent No.

5 1,963,840, issued June 19, 1934. This method is particularly eflicacious for the production of a low purity oxygen, that is, having an oxygen content of from 45-50%, or, in other words, for the separation of approximately two-thirds of the nitrogen contentof the air.

It is an object of the invention-to provide a process for the separation of gaseous mixtures which results in the obtainment of components of a high but not complete purity.

Another object of the invention is the provision of a process for the separation of a gaseous mixture into components wherein the resolution is effected with a lower consumption of power with respect to the elimination of the amount of lower boiling component of the gaseous mixture and to the obtainment of the higher boiling component in a state of higher purity.

An additional object of the invention is to provide a process for the separation of gaseous mix- 5 tures, especially air, into oxygen of a purity of from 75% to 80% by partial liquefaction of a greater portion of the amount of air to be separated (about 60-75%), whereas from the remaining portion (25-40%) the oxygen is separated without compressing the air.

A further object of the invention is to provide a process for the resolution of a gaseous mixture into components in which a compressed and cooled gaseous mixture is partially liquefied in a plurality of stages, and the liquid so produced vaporized in a plurality of stages at difierent pressures on the vaporizer side of condensers with a rectification taking place in the first vaporizer.

A specific object of the invention is the provision of a process for the resolution of air into nitrogen and nitrogen containing oxygen, wherein a liquid of -90% oxygen content may be obtained by vaporization and rectification in a first vaporizer.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or'more of such steps with respect to each of the others thereof, which will be exemplified in the process hereinafter disclosed, and the scope of the application of which will be indicated in the claims.

In the practice of the invention a gaseous mixture is separated into components by compressing and then cooling to a low temperature. The cooling of the gas is effected by passage through a cold yielding zone and preferably by conducting the same in direct contact with cold regenerative bodies which have previously been brought to a low temperature by contact with cold separated components. The flow of ingoing gas and outgoing components may be periodically and alternately reversed with respect to a given regenerative body. The cooled gaseous mixture is now separated into higher and lower boiling components by partial liquefaction in a plurality of stages which may be arranged in series. The first partial liquefaction effects the formation of a liquid enriched in higher boiling component and a gas or a vapor enriched in lower boiling component, which is then partially liquefied in a second condenser.

The liquid component so obtained in the second condenser is conducted to a by-rectifier wherein it fiows countercurrently to vapors arising from the first vaporizer and there results a liquid product having a considerably higher content of higher boiling component. Such liquid is admixed with that arising from the first partial liquefaction, prior to entry into the first vaporization stage where it is partially vaporized with simultaneous rectification to a high content of higher boiling component. The liquid so obtained in the first vaporization is then further and completely vaporized in a second stage at a pressure which is lower than that of the earlier stage. The vaporization in the later stage under a lower pressure is effected by flowing, more particularly by trickling, a liquid preferably countercurrently in continuoiu uni-directional indirect heat exchange relation with the gas mixture. More particularly the liquid may be in contact with the entire heat exchange surface and have 5 cocurrent flow in a continuous manner'in thin streams with continuity of direct contact of vapor and liquid. Higher and lower boiling components in gaseous form are warmed prior to. use, or storage, by passing separately through cold absorbing zones. 'The cold absorbing zones may be in the form of regenerators through which the components pass in direct contact with regenerative bodies. Further, the non-liquefied portion of the lower boiling component vapors in compressed state may be expanded by conducting it through an expansion turbine whereby cold losses are recovered.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in

which Fig. 1 illustrates diagrammatically an. ap-

! paratus suitablefor accomplishing resolution of the gaseous mixture into components according to' the novel procedure herein described, and Fig.

2 depicts a modification of the apparatus shown in Fig. 1 whereby a portion of the cooled gaseous mixture is led into a by-rectifler.

The apparatusiFig. 1) comprisesin combination a plurality of regenerators I, 2, 3 and 4 which are operated in pairs for cooling an ing'oing gas eous mixture andabsorbing cold from outgoing separated components. The re'generators are subjected .to alternate and periodical reversal throughthe medium of reversing valves 51, 5:, I: and 54 positioned at the tops thereof. By means of suitable conduits Positioned in operative relation the'regenerators are connected with aseparating means 40. The separating means is divided into compartments by .suitably positioned diaphragms and therein is effected a partial liquefaction of a gaseous mixture with simultaneous rectification. A rectifying column 3i is operatively connected with the separating means, and

by means of a conduit the top of the second condenser is connected with an expansion turbine 50. The conduits through which the gaseous mixture and separated components are passed are provided with suitable valves, some of which are of the expanding type, by means of which the flow of gaseous mixture and components to and from the separating apparatus is controlled.

Operation for the separation of a gaseous mixture into components may be carried out in the following manner. The procedure will be illustrated with respect to the separation of air into an oxygen and a nitrogen component. It will be realized that the process is not limited to the separation of air, and that reference to air here- 60 .inafter is wholly illustrative.

The air to be separated may be compressed in the usual manner to approximately two atmospheres (absolute). The thus compressed air is cooled by passing through two of the four regen- 65 erators l, 2,3 and 4 alternately, from whence the cooled and compressed air passes, for example, having been cooled in regenerators I and 2 through conduits 9, III, l5 and ii to a pipe II which introduces it into the base of a separating means 40. In the separating means it passes through two condensers or and 44 in'series. A separation or resolution of the air is brought about in the separating column 40 so that there'is effected a partial separation of 75 nitrogen by means of partial liquefaction and .of pipe 23 having vaporizer 46. It is introduced into this vaporizer conduits l6 and II -ried out in a manner liquefying stages 43 fractional condensation in the two condensers. These condensers are connected in series in such a way that the entire oxygen content of the air,

together with a practically equal volume of nitrogen, is condensed in the first condenser 43 in and I: to the regenerator 4 fromwhich it passes through conduit l4, reversing valve 54 and conduit vaporizing chamber surrounds the tubes forming the vaporizer side of the condenser 43, and is provided with trays to assist in the rectification or enrichment, of the liquid in oxygen content. Approximately three-fifths oi" the introduced liquid is vaporized in the vaporizer 45 with simultaneous rectification, the vapors and liquidflowing in countercurrent relation to one another, and 1 there results a liquid containing vapproximately 80% oxygen. -This liquid is conducted by means 11 expansion valve 24 to the and passes, out at the bottom through conduit. Thence it passes through iswithdrawn through conduit 83, reversing valve 53 and pipe 13. e The partial liquefaction is eil'ected at a pressure of about two atmospheres, the vaporizationa pressure of'about one.

in the vaporizer 45 at atmosphere, and that in vaporizer 48 at a reto regenerator 3 from which it duced pressure, e. g., approximately 0.5 atmosphere. The condenser 43 traverses the whole of the vaporizing chamber part of the vaporizing chamber 46, whereas the condenser 44 traverses only the upper part of collects upon the diaphragm from which. it may be conducted through pipe 29 provided with valve 30 to the rectifier 3|.

Vapo'rization' in the vaporized (approximately three-fifths) during its downward flow, and is thereby enriched to approximately 80% oxygen content through simultaneous rectification, which is augmented by means of the rectificationtrays 41. In this va- 45 and a considerable vaporizing stage 45 is 'car such that the liquidcontalning approximately 45% oxygen coming from trays.

porizationstage the vapors flow upwardly through the trays or plates 41, are conducted from the vaporizer. by the conduit 2| and introduced into the rectifier 3|. v This rectifier is also provided with rectifying trays 32. The rectifier,

3| serves to remove oxygen contained in the vapors passing from the vaporizer 45, and the rectification is eflected by means of nitrogen wash liquid introduced through the conduit 29 and arising in the condenser 44. The liquid nitrogen consisting of approximately one sixth of the air volume introduced to be separated is introduced on to the head of the rectifier and washes the oxygen out of the vapors entering at the bottom thereof through the conduit 2| and arising from vaporizer 45. In the rectifier is thus obtained an additional 15% of a liquid containing approximately 50% oxygen. Such liquid leaves the rectifier through the conduit 22, and joins that arising in the condenser 43, and entering the vaporizer 45 through the conduit 20.

The liquid formed in the vaporizer 45 is conveyed to the vaporizer 46 which is constructed in the form of a trickle evaporator provided with The liquid enriched in oxygen to about 80% is introduced at the top of this vaporizer, fiows downwardly with cocurrent fiow of vapor and liquid, is wholly evaporated and leaves by means of the conduit 25. In Fig. 2 the liquid oxygen is introduced at the bottom of the second stage vaporizer, is completely evaporated and leaves at the top by the conduit 25. The oxygen vapors are removed from the vaporizer 46 under a reduced pressure of about 0.5 atmosphere, and are warmed prior to exit by passing through a regenerator, either 2 or 3.

The operation of the vaporizer 46 which may have cocurrent flow of liquid and vapor is accompanied by several advantages. However, if it is desired to waive these advantages this vaporizer could, if required, be of the customary construction and mode of operation, that is, filled with liquid from which vapors would bewithdrawn in an upward direction. It is desirable,

' however, always to operate the vaporizer 45 in such a manner. that the'vapors are conducted upwards in countercurrent relation to the liquid, that is, flowing cocurrently with the gas mixture which is undergoing condensation or partial liquefaction on the condenser side. The liquid in this vaporizer flows downwardly in countercurrent relation both to the vapors being evolved and to the flow of the gas mixture un dergoing liquefaction.

It is inthis manner that it is possible to ac- .complish liquefaction of the low purity oxygen of approximately is to be withdrawn at the bottom and conducted to the vaporizer 46. Such a liquid could not be withdrawn from the top because the liquid at that point has an oxygen content of only 45-50%. The oxygen resulting in the separation of air is withdrawn from the vaporizer 46 at approximately 0.5 atmosphere absolute, and is alternately led out through regenerators 2 and 3.

Thenitrogen arising from the rectifier 3| and from the separating means 40, after expansion of that arising in the separating column in an expansion turbine 50, is united and led out alternately through regenerators and 4. It will thus be observed that while one pair of regenerators is functioning to cool ingoing air, the other pair of regenerators acts as a cold absorbing zone and takes up cold from outgoing separated oxygen and nitrogen. The fiow of ingoing air and outgoing oxygen and nitrogen is reversed alternately and periodically in rapid sequence,

;for example, every two to three minutes.

tent liquid requires a pressure difl'erential of 1:2.

In the foregoing process, however, it is desired that the entire quantity of air be first conducted through the condenser 43 and then through the condenser 44, and in view of the fact that a pressure of only two atmospheres is permissible in condenser 43 'it is impracticable to. bring this pressure to four atmospheres prior to conductance to condenser 44. According to the present invention this difiiculty is overcome by a reduced or sub-pressure of approximately 0.5 atmosphere in the vaporizer 46. This is effected by withdrawing the oxygen under such reduced pressure with a result that the pressure relationship of 1:4

is set up.

The procedure may also be carried out in that a quantity of air equal to the amount of oxygen withdrawn at a pressure of approximately 0.5' atmosphere through regenerators 2 and 3 is blown without excess pressure alternately and periodically through such regenerators into the rectifier 3|. In the rectifier it contacts with the wash nitrogen and is separated into a liquid enriched in oxygen and nitrogen in gaseous state. When so operating less of the low purity oxygen is liquefied in condenser 43, but more nitrogen' must be liquefied in the condenser 44, as wash nitrogen. This additional amount is approximately double that required when introducing the air at two atmospheres and withdrawing oxygen at 0.5 atmosphere, and amounts approximately to 20% of the entire volume of air whereas when operating without the blowing in procedure only about 15% of the air to be separated is required as wash nitrogen. (This case being' illustrated in Fig. 2 of the accompanying drawings.)

The mode of carrying out the process shown in Fig. 2 differs from that in Fig. 1 only in that that portion of the gaseousmixture to' be separated which is alternately introduced through re generators 2 and 3 in cold exchange relation-with the higher boiling constituent, is not liquefied but is directly blown into rectifier 3| through conduit 48 without excess pressure, and that the higher boiling constituent of this portion is washed out in this rectifier by the medium of the wash liquid. I

Thus. for example, if 10,000 cubic meters of air per hour are to be separated into approxi' mately 80% oxygen and technically pure nitrogen without a blowing in of a part of the air, a lique- 7 5 -cases 6,000 cubic meters of air must be compressed to two atmospheres for liquefaction and 2,500 cubic meters of oxygen withdrawn at 0.5 atmosphere. In the second case an additional 2,500 cubic meters of air must be blown into the rectifier 3| at a pressure of about 1.1 atmospheres. In practice, however, 10,000 cubic meters must be compressed, in the first case,

inasmuch as 4,000 cubic meters of nitrogen separated in compressed condition are conducted to the expansion turbine for expansion whereby the cold losses of the plant are covered. In the second case, on the other hand, 7,500 cubic meters of air must be compressed,'6,000 cubic meters thereof are liquefied and 1,500 cubic meters are conducted to the expansion engine or turbine, whereas 2,500 cubic meters are blown in without excess pressure.

The process hereinbefore described is of partioular practical importance when utilized in connection with regenerators which are operated periodically with alternation of flow of ingoing gas and separated components. This is the case inasmuch as the foregoing method of vaporization results in an appreciable reduction of the pressure required under which the gas mixture is condensed, while on the other hand the volume becomes somewhat greater due to withdrawal of a separated component under reduced pressure. With a lowering of the pressure there is an increase in the heat transfer surfaces required for cold exchange between the gas mixture and separated components whereby cooling to liquefaction temperature is occasioned and such cooling always precedes the separation.

The production of oxygen of approximately 70-90% purity appliesespecially to plants having large capacities inasmuch as such plants are designed for large scale manufacturing operations, such asarc found in the iron and steel, the chemical and metallurgical industries, and also others in which operations are conducted at high temperature. The production costs of such plants are materially affected by the cost of the cold exchangers, and since the efficiency of cold exchange is a determining factor in the consumption of power, and further, inasmuch as the cold losses cannot be materially reduced with the continuously operating tubular type of cold exchanger, it will be realized that the procedure herein described is of special importance, and especially designed for use in conjunction with cold accumulators through which the gases and components flow periodically in alternation.

Since certain changes may be made in carrying out the /above process without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A process for the resolution of gaseous mixtures, which comprises cooling a gaseous mixture by conducting it through a cold yielding zone, partially and fractionally liquefying said cooled gaseous mixture in a first stage whereby the content of higher boilingtconstituent is gradually decreasing in an upward direction, producing wash liquid for a by-rectification stage by condensing another portion of the gaseous mixture l'argely freed of higher'boiling constituent in a second stage, said wash liquid consisting substantially of lower boiling constituent, conducting the higher boiling constituent enriched liquid obtained in the first stage of fractional liquefaction to a first stage of vaporization, vaporizing this liquid with simultaneous rectification whereby said liquid is enriched in higher boiling constituent while the lower boiling constituent, together with a small portion of higher 3:

boiling constituent is evaporated, said evaporated lower boiling constituent being conducted to a by-rectification stage wherein the higher boiling constituent is washed out by the medium of the liquid arising from the second condensation stage whereby this liquid is enriched in higherboiling constituent, conducting said higher boiling constituent enriched liquid to the first vaporization stage whereit joins the liquid arising from the first condensation stage, partially vaporizing this liquid now formedwhile the remaining portion of this liquid is conducted to a second vaporization stage where it is wholly vaporized at reduced pressure, warming the vapor arising and the lower boiling constituent separated partly at excess pressure and partly at atmospheric pressure, by conducting them through cold absorbing zones.

2. A process for the resolution of gaseous mixtures, which comprises cooling a compressed gaseous mixture by conducting it through a cold yielding zone, partially and fractionally liquefying said gaseous mixture in a first stage wherebythe content of higher boiling constituent is gradually decreasing in ]an upward direction, producing wash liquid for a by-rectiflcation stage by condensing another portion of the gaseous mixture .largely freed of higher boiling constituent in a second stage, said wash liquid consisting substantially of lower boiling constituent, conducting the higher boiling constituent enriched liquid obtained in the first stage of fractional liquefaction to a first stage of vaporization, vaporizing this liquid with simultaneous rectification whereby said liquid is enriched in higher boiling constituent while the lower boiling constituent, together witha small portion of higher tion stage whereby this liquid is enriched in,

higher boiling constituent, conducting said higher boiling constituent enriched liquid to the,

first vaporization stage where it .joins the liquid arising from the first condensation stage, partially vaporizing this liquid now formed while the remaining portion of this liquid is conducted to a second vaporization stage where it is wholly vaporized at reduced pressure, warming the vapor arising and the lower boiling constituent separated partly at excess pressure .and partly at atmospheric pressure, by conducting them through cold absorbing zones, after having expanded the lower boiling constituent separated in compressed condition in order to cover cold losses.

3. A process, for the resolution of gaseous mix- 5 tures, which comprises cooling a gaseousmixture partially compressed and partially inblown in uncompressed state by conducting it through this liquid with simultaneous rectification where-.

by said liquid .is enriched in higher boiling constituent while the lower boiling constituent together with a small portion of higher boiling 25 constituent is evaporated, said evaporated lower boiling constituent being conducted to a by-rectification stage wherein the higher boiling constituent is washed out by the medium of the liquid arising from the second condensation stage 30 whereby this liquid is enriched in higher boiling constituent, conducting said higher boiling constituent enriched liquid to the first vaporization stage wherein it joins the liquid arising from the first condensation stage, partially vaporizing this 35 liquid now formed while the remaining portion of this liquid is conducted to a second vaporization stage where it is wholly-vaporized at reduced pressure, while the portion inblown in uncompressed state is conducted to a rectifying stage 40 in order to wash out the higher boiling component from said inblown portion of the gaseous mixture, warming the vapor arising and the lower boiling constituent separated partly at excess pressure and partly at atmospheric pres- 45 sure, by conducting them through cold absorbing zones, after having expanded the lower boiling constituent separated in compressed state in order to cover cold losses.

4. A process for the resolution of gaseous mix- 50 tures, which comprises cooling a gaseous mixture by conducting it in contact with regenerative bodies, partially and fractionally liquefying said cooled gaseous mixture in a first stage .whereby the content of higher boiling constituent is grad- 55 ually decreasing in an upward direction, producing wash liquid for a by-rectification stage by condensing another portion of the gaseous mix--.

constituent is washed out by themedium of the liquid arising from the second condensation stage wherebythis liquid is enriched in higher boiling constituent, conducting said higher boiling con- 7 stituent enriched liquid to the first vaporization stage where it joins the liquid arising from the first condensation stage, partially vaporizing this liquid now formed while the remaining portion of this liquid is conducted to a second vaporization stage where it is wholly vaporized at reduced 5 pressure, warming the vapor arising and the lower boiling constituent separated partly at excess pressure andpartly at atmospheric pressure, by conducting them in contact with regenerative bodies. 10

5. A process for the resolution of air, which comprises compressing a greater portion of the airto be separated to about 2 atmospheres and a smaller portion to about 1.2 atmospheres, chilling the air by passing it in direct contact with cold regenerative bodies, separating the thus cooled air into a liquid component enriched in oxygen and a gaseous component containing nitrogen in two stages in series, vaporizing the liquid component thus obtained in two stages, the first stage of vaporization being effected with accompanying rectification at a pressure of about 1 atmosphere with countercurrent fiow of vapor and liquid, rectifying the vapors produced during said first stage of vaporization in a by-rectifying stage and returning liquid produced by the rectification to the first stage, conducting the liquid obtained in the first evaporation stage to the second stage and efiecting the second stage of vaporization at a pressure of about 0.5 atmosphere by trickling liquid resulting from the first stage countercurrently in continuous uni-directional indirect heat exchange relation with the air undergoing liquefaction, said liquid being in contact/"with the entire heat exchange surface and with cocurrent fiow in a continuous mannr in thin streams with continuity of direct contact of vapor and liquid, warming the oxygen and nitrogen components by passing them in direct contact with warm regenerative bodies, expanding the nitrogen separated in compressed condition, and alternately and periodically reversing the fiow of ingoing air and outgoing oxygen and nitrogen with respect to the regenerative bodies.

6. A process for the resolution of gaseous mixtures, which comprises cooling said gaseous mixture, partially liquefying at uniform condensation pressure in two stages arranged in series whereby liquid enriched in higher boiling component is obtained, vaporizing the liquid thus obtained in two stages, the first stage being effected by vaporizing the liquid enriched in higher boiling component and containing initially a considerable amount of lower boiling component at v a pressure greater than that present in the second stage of vaporization, said first stage of vaporization being attended by rectification whereby a smaller portion of liquid more highly enriched in higher boiling component is obtained, and vaporizing the remaining liquid so produced in a, second stage of vaporization at a reduced pressure by fiowing the liquid in continuous unidirectional indirect heat exchange relation with the gas mixture, the liquid being in contact with the heat exchange surface and having cocurrent flow in a continuous manner with continuity of direct contact 'of vapor and liquid.

. tion with the gas mixture, said liquid being in contact with the heat exchange surface and having cocurrent flow in a continuous manner with continuity of direct contact of vapor and liquid.

8. A process for the resolution of a gaseous mixture, which comprises vaporizing a liquid en-' riched in a higher boiling component in two stages at different pressures, the first stage being accompanied by simultaneous rectification, and the 10 second stage effecting complete evaporation of the liquid enriched in higher boiling component by the rectification in the first stage of vaporization, said complete evaporation being brought about by flowing the liquid in continuous uni-directional heat exchange relation with the gas mixture undergoing liquefaction, said liquid being in contact with the heat exchange surface and having cocurrent fiow in a continuous manner with continuity of direct contact of vapor and liquid.

9. In a process for the resolution of air into oxygen and nitrogen, the improvement which comprises vaporizing a liquid enriched in oxygen in two stages at different pressures one of said pressures being sub-atmospheric the vaporization of the oxygen liquid in the second stage being effected by trickling the liquid resulting from the first stage countercurrently in continuous uni-directional indirect heat exchange relation with the air undergoing liquefaction, said liquid being in contact with the entire heat exchange surface and having cocurrent flow in a continuous manner in thin streams with continuity of direct contact of vapor and liquid.

10. In a process for the resolution of air into oxygen and nitrogen, the improvement which comprises vaporizing a liquid enriched in oxygen in two stages at different pressures, the first stage being at about atmospheric pressure and the sec- 0nd stage at asub-atmospheric pressureof about 0.5 atmosphere absolute by trickling the liquid formedin the first stage countercurrently in continuous uni-directional indirect heat exchange a relation with the air undergoing liquefaction, said liquid being in contact with the entire heat exchange surface and having cocurrent fiow in a continuous manner in thin streams with continuity of direct contact of 'vapor and liquid.

11. A process for the resolution of a gaseous mixture, which comprises cooling said gaseous mixture, partially liquefying in two stages whereby a liquid enriched in a higher boiling component and a gas enriched in a lower boiling component are obtained, vaporizing the liquid obtained in two stages at different pressures, the first stage of vaporization being effected with countercurrent flow of liquid and vapors and simultaneous rectification, and the second stage with cocurrent fiow of liquid and vapors and accompanying complete vaporization, warming the higher boiling component substantially to atmospheri'c temperature, and warming the por tion of lower boiling component separated in compressed state by liquefaction of a small portion of compressed gas, expanding said lower boiling component whereby cold losses are covered, further warming said lower boiling component substantially to atmospheric temperature.

12. A process for the resolution of a gaseous mixture, which comprises cooling said gaseous mixture, partially liquefying the cooled gas mixture in two stages having countercurrent liquid and gas flow, and vaporizing liquid so produced in two stages, the liquid and vapors flowing coun- .75 tercurrently with respect to one another in the first stage, and eifecting the vaporization in the second stage by trickling liquid resulting from an earlier stage countercurrently in continuous uni-directional indirect heat, exchange relation with the gas mixture, said liquid being simultaneously in contact with the entire heat exchange surface and with vapor and liquid.

13. A process for the resolution of a gaseous mixture, which comprises cooling said gaseous mixture, partially liquefying'the cooled gas mixture in a plurality of stages having countercurrent liquid and gas flow, and vaporizing liquid so produced in a plurality :of stages, the liquid and vapors flowing countercurrently with respect to one another in an earlier stage, and effecting the vaporization in a later stage under reduced pressure by trickling liquid resulting from an earlier stage countercurrently in continuous unidirectional indirect heat exchange relation with the gas mixture, said liquid being in contact with said air to about 2 atmospheres, cooling, liquefying said compressed and cooled air with accompanying fractionation and rectification in two stages arranged in series and having countercur-fl rent fiow of gas and liquid whereby there is produced a liquid enriched in oxygen, vaporizing said liquid in two stages, the first stagebeing carried out at a pressure of about 1 atmosphere with countercurrent fiow of liquid and gas giving simultaneous rectification, and the second stage being effected under a pressure of about 0.5 atmosphere by trickling liquid resulting from the first stage countercurrently in continuous unidirectional indirect heat exchange relation with the air, said liquid being in contact with the entire heat exchange surface and with cocurrent flow in a continuous manner in thinstreams with continuity of direct contact of vapor and liquid.

15. A process for the resolution of a gaseous mixture which comprises cooling said gaseous mixture, partially liquefying the cold gaseous mixture in a plurality of stages having countercurrent liquid and gas flow and vaporizing liquid so producedin a plurality of stages, the liquid and vapors flowing countercurrently with respect to one another in an earlier stage of vaporization, and effecting the vaporization in a later stage by flowing liquid resulting from an earlier stage in continuousuni-directional indirect heat exchange relation with the gaseous mixture, said liquid being simultaneously in contact with the heat exchange surface and with vapors produced, and flowing cocurrently with said vapors.

16. A process for the resolution of gaseous mixtures which comprises cooling a gaseous mixture by conducting it through a cold'yielding zone, partially liquefying said cooledgaseous mixture in a plurality of stages whereby a liquid enriched in a higher boiling constituent anda gaseous lower boiling component are obtained.

vaporizing said liquidin a plurality of stages at different pressures, the vaporization in one of said stages being effected by flowing liquid resulting, from an earlier stage in continuous unidirectional indirect heat exchange relation with warming the vapors arising from said vaporization and the gaseous lowerboiling component by conducting them through cold absorbing zones.

1'7. A process' for the resolution of gaseous mixtures, which comprises cooling a gaseous mixture by conducting it through a cold yielding zone, partially liquefying flsaid cooled gaseous mixture at uniform condensation pressure in a plurality of stages whereby a liquid enriched in a higher boiling constituent and a gaseous lower boiling component are obtained, vaporizing said liquid in a plurality of stages at different pressures, the vaporization in one of said stages being effected by flowing liquid resulting from an earlier stage in continuous uni-directional indirect heat exchange relation with the gas mixture. said liquid being in contact with the heat exchange surface and having cocurrent flow in a continuous manner with continuity of direct contact of vapor and liquid, subjecting vapors arising in a preceding vaporization stage to rectification, and returning liquid so produced to said vaporization stage, and warming the vapors arising from asucceeding stageof vaporization and the gaseous lower boiling component by conducting them through cold absorbing zones.

18. A process for the resolution of air, which comprises compressing air, chilling the compressed air by contacting with cold regenerative bodies, separating the thus cooled air into a liquid component enriched in oxygen and a gaseous component enriched in nitrogen in a plurality of stages, vaporizing the liquid component in a' plurality of stages at different pressures, the vaporization in one of said stages being effected by flowing liquid resulting from an earlier stage in continuous and uni-directional indirect heat exchange relation with the gas mixture, said liquid being in contact with the heat exchange surface and having cocurrent flow in a continuous manner with continuity of direct contact of vapor and liquid, and warming the oxygen enriched and nitrogen enriched components 'by conducting said components in contact with regenerative bodies.

1 9. A process for the resolution of a gaseous mixture, which comprises cooling said gaseous mixture, partially liquefying the cold gaseous mixture with countercurrent liquid and gas flow, and vaporizing liquid so produced in a plurality of stages, the liquid and vapors flowing countercurrently with respect to one another in an earlier stage of vaporization, and effecting the vaporization in a later stage by flowing liquid resulting from an earlier stage in continuous uni-directional indirect heat exchange relation with the gaseous mixture, said liquid being simultaneously in contact with the heat exchange surface and with vapors produced, and flowing cocurrently with said vapors.

20. A process for the resolution of a gaseous mixture, which comprises cooling said gaseous mixture, partially liquefying the cold gaseous mixture and vaporizing liquid so produced in a plurality of stages, the liquid and vapors flowing countercurrently with respect to one another in an earlier stage of vaporization, and efiecting the vaporization in a later stage by flowing liquid resulting from an earlier stage in continuous unidirectional indirect heat exchange relation with the gaseous mixture, said liquid being simultaneously in contact with the heat exchange surface and with vapors produced, and flowing cocurrently with said vapors.

' MATHIAS FRANKL. 

